Hydraulic governor system



6 Sheets-Sheet l In venters A itorneyg G. H. MURRAY ET AL HYDRAULIC GOVERNOR SYSTEM Oct. 19, 1954 Filed July 23, 19.53

f6 Sheets-Sheet 2 Ir; Denton;

Attorneys Oct. 19, 1954 G. H. MURRAY x-:T AL

HYDRAULIC GOVERNOR SYSTEM Filed July 2s, 195s I 2 wwe? f Anl-@Ilan Oct. 19, 1954 G, Hl MURRAY ETAL 2,692,132

HYDRAULIC GOVERNOR SYSTEM Filed July 23, 1955 6 Sheets-Sheet 5 339 03X35/ 36 (D 352 3 //35 335 j A 334 37 y 337 334 f 332 7% ,l I /9 A Uenors A wlw d By Z/ www@ A itorneys' Oct. 19, 1954 G. H. MURRAY ET AL HYDRAULIC GOVERNOR SYSTEM Filed July 23, 1953 6 Sheets-Sheet' 4 Inventors m B l; www?" A ttorneys HYDRAULIC GOVERNOR SYSTEM Filed July 23, 1953 6 Sheets-Sheet 5 6 F/Gvl.5.

ttorney Filed July 25. 195:5

Oct. 19, 1954 G. H. MURRAY ET AL 2,592,132

HYDRAULIC GOVERNOR SYSTEM 6 Sheets-Sheet 6 npentprs @wmw Patented Oct. 19, 1954 'i E, T O F F I C E HYDRAULIC GVERNOR SYSTEM British company Application July 23, 1953, Serial No. 369,849

Claims priority, application Great Britain July 28, 1952 l1 Claims.

This invention relates to hydraulic governor systems, particularly for internal combustion engines, of the kind comprising a positive displacement pump driven at a speed proportional to the speed of the engine, a leak valve controlling the effective cross-section of the path by which fluid delivered by the pump can escape, a speed control member associated with the engine, for example with the fuel supply to the engine, to control the speed thereof, and hydraulic apparatus responsive to pressure changes due to changes in the rate of delivery of the pump arranged to actuate the speed control member.

In hydraulic governor systems of this general kind it has been found that the hydraulic appan ratus responsive to changes in the rate of delivery of the pump tends to be over-sensitive, with the result that over-correction of the speed control member causes engine hunting or speed instability. It has already been proposed to provide a connection between the leak valve and the speed control member Iwhereby movement or the speed control member caused by the hydraulic apparatus acts to open or close the leak valve and thus dampen, or to some extent counteract the movement imparted by the hydraulic apparatus, and so to stabilise the governor. It will be apparent that in any case by varying the setting of the leak valve it is possible to control the speed at which the engine is to operate.

It is an object of the present invention to provide an improved hydraulic governor system of the kind referred to, including such a leak valve, which will provide for limiting the range of movement of the speed control member, and thus the maximum amount of fuel which can be sup plied to the engine, at any particular engine speed.

A hydraulic governor system according to the present invention comprises a displacement ,f

pump driven at a speed proportional to that of the engine, a working piston acting directly or indirectly on the speed control member of the engine, and acted upon by uid pressure derived from the pump', a leak valve arranged in the '2' hydraulic circuit of the piston to control escape of iiuid therefrom and connected directly or indi rectly with the working piston so as to be moved automatically in response to movements of the piston, means for adjusting the datum setting i of the leak valve to control the speed at which the engine is to operate, and apparatus for preventing the supply of excess fuel to the engine at any setting of the governor apparatus, comprising a stop piston or the equivalent subject to a pressure dependent upon the engine speed, and means whereby such stop piston acts to resist or prevent movement of the speed control member in a direction to increase the fuel supply tc the engine beyond a point which varies with and is determined by the engine speed.

Preferably the stop piston is subject to pressure derived from the displacement pump which supplies fluid to the hydraulic circuit of the worku ing piston. Moreover the working piston is preferably doublesided, with the chamber on one side connected directly or indirectly to the delivery side of the displacement pump, while the chamber on the other side is connected to relief through the leak valve, and to the chamber on the rst side through a spring-pressed release valve, 'whereby an increase in the flow from the pump is reflected as an increase in pressure on the second side of the Working piston, relative to the pressure on the rst side thereof.

According to a preferred feature of the invention the governor system includes a pressure reducing valve between the delivery side of the pump and the chamber on the rst side of the working piston, the pressure reducing valve being so constructed that the pressure drop across the valve is approximately proportional to the flow through the valve, and thus to the speed of the engine, and in which the stop piston is double sided and its two sides are subject to the pressures respectively on the two sides of the pressure reducing valve. In such case the connection between the chamber on the first side of the working piston and the delivery side of the displacement pump is preferably by Way of the pressure reducing valve.

Conveniently the Working piston and the stop piston are arranged at opposite ends of a single cylinder, the pump pressure being admitted direct to the side of the stop piston remote from the working piston, while the low pressure side of the pressure reducing Valve is connected to the intermediate part of the cylinder between the working piston and the stop piston, the side of the working piston remote from the stop piston being subject to the so called working pressure between the release valve and the leak valve.

According to another preferred feature of the invention the governor system includes a spring assembly arranged to act on the stop piston, such spring assembly comprising a rst spring which is operative throughout the travel of the piston, and a second spring which is operative only at positions of the piston corresponding to relatively higher engine speeds.

The system may include a lost motion connection between the stop piston and the speed control member of the engine, and a resilient con-1 nection between the working piston and the speed control member of the engine, so that within the limits of the lost motion connection the speed control member is controlled by the working piston, whereas for movement of the working piston beyond these limits. thev resilient connection associated with the working piston is distorted, and the speed control member is controlled by the stop piston.

Preferably the governor system includes a manual operating control for the engine speed control member, and an override device which, on movement of the manual operating control through a predetermined distance towards the off or stop position, acts to disconnect the working piston from the speed control member. Moreover the system may include an emergency control device which acts to disconnect the work-- ing piston from the speed control member of the engine, and to connect the manual operating control thereto.

Thus in one form of the invention, the working piston is connected to the engine speed control through a dog clutch or similar device, one part of the clutch being urged by a spring or other means into engagement with the other part, and the manual operating control is connected to the engine sped control ethrough a lost-motion connection including cam or other means. which are arranged on movement of the manual operating control sufficiently to take up the play in the lost motion connection in the direction to stop the engine, to disengage the two parts of the dog clutch against the force of the spring.

In this case it is preferred to include an emergency control device to locate the two relatively movable parts of the lost motion connection in the position in which the two parts of the dog clutch are disengaged, whereby the manual operating control becomes solely effectiveA to control the engine speed control member.

The invention may be carried into practice in various ways but one specific embodiment of the invention as applied to a fuel-injection type internal combustion engine is shown by way of example in the accompanying drawings, in which Figure 1 is a sectional side elevation showing diagrammatically the arrangement which is shown in more detail in the remaining figures,

Figure 2 is a` sectional side elevation showing in detail part of the apparatus including the working piston acting on the speed, control member of the engine the. stop piston, the leak valve, and associated mechanism,

Figure 3 is a sectional side elevation in the same plane as and partly overlapping Figure 2 showing the hydraulic servo mechanism through which the working piston acts on the speed control member of the engine,

Figure 4. is a sectional side elevation in the same plane as, and partly overlapping Figures 2 and 3, and shows part of the pump by which the working fluid acting on the working piston is supplied and also the combined booster valve and return spring assembly for the servo piston of the hydraulic servo mechanism,

Figure 5 is a cross-section on the line V-V in Figure 2, showing the release valve arranged between the high and low pressure` chambers of the working piston,

Figure 6 is a sectional elevation in the same plane as and partly overlapping Figure 5 showing .special mechanism including a, manual override control by which the speed control member is connected to the working piston,

Figure 7 is a perspective view partly broken away of the. mechanism shown in Figure 6 showing certain details of the arrangement shown therein, and

Figures 8 and 9 are respectively an enlarged perspective view and an enlarged sectional View of details of the mechanism shown in Figures 6 and 7 It is to be noted that Figures 2, 3 and 4 taken together represent a cross section in one plane of the complete hydraulic apparatus or' system and that these figuresoverlap oney another somewhat toA make clear their relationships to one another.

The governing system. illustrated will first be described in general terms by reference to the diagrammatic Figure 1, and then: in greater detail with reference to the remaining figures of the:

drawings.

The governor' system comprises a displacement pump l of the gear type driven directlyi or indirectly from. the engine at a speed: directly proportional to engine speed, and arranged to deliver hydraulic fluid to hydrau'lic'control mechanism which is connected through a hydraulicservo device to the fuel control shaft 2i of the fuel. injection pumps of the engine.

The hydraulic. control mechanism; contained in a housing. 3 having. three parallel? bores or chambers A, 5 andI 6, within and between which are provided theA component valves, pistons, spring assemblies and hydraulic connections of the mechanism. Hydraulic Huid from the displacement pump l` is admitted-.adjacent the lower end of the first (il) of the three chambers and passes through a spring-loaded. pressure reducing valve 'I to a space: 8 above the valve. The pressure reducing valve l is so constructed that the prese sure drop across itis approximately proportional to the flow` of uid through it, and since. the output of the pump l is approximately proportional to engine speed, and substantially the whole of the output passes` through the valve, the pressure drop is. therefore approximately proportional to engine speed. It-will be noted however that the pressure drop is independent of the actual pressure level in the circuit.. The pressure of the fluid on the downstream side of the valve 'i will be. referred to hereafter for convenience as the balance pressure,v while the pressure on the upstream side ci the valve will be called the pump delivery pressure.

Having passed through the pressure reducing valve 1 the hydraulic fluid ilows through a crossdrilling into a mid-fportionof the. second 5V of the three chambers,` where the balance pressure acts on one side of a double-sidedworking piston 81o-,- cated in one half of. the chamber and hereinafter assumedv to be theupper half., and acts also on the adjacent or upper side of a double-sided lstop piston li) located in the lower half of the chamber. The fluid then passes through another crossdrilling into the lower part of the third chamber which contains a spring loaded sleeve valve Il arranged to uncover escape ports in an upper part of the third chamber, and actuated by a piston l 2 (hereinafter called the release valve piston) sliding within the third chamber 6v and subject on its lower side to the balance pressure. The upper side of the release valve piston i2 is subject to fluid at tank pressure in the internal cavity 5@ which pressure may be atmospheric, or may be maintained at a constant relatively low value. This spring loaded sleeve valve il therefore acts as a release valve to control the balance pressure. After passing through the escape ports in the third chamber t the hydraulic -duid passes back through a cross drilling into a gallery i3 surrounding the upper part of the first and second chambers d and 5. The gallery E3 communicates through restricted orifices ld with the upper part of the second chamber Si where the pressure of the fluid which will hereafter be referred to as the working pressure, acts upon the upper side of the doubie-sided working piston 9 and also through a further orifice i5 with the upper part of the first chamber l from which it escapes through an adjustable leak orifice, controlled by a leak valve l@ to the space il@ subject to tank pressure.

The upper side of the working piston 9 is acted upon by a compression spring il and the piston is connected through a Spring-biased lost-motion device to a control rod i8 passing through a gland in the upper part of the second chamber 5, this control rod it being indirectly connected, as will be described below, through a hydraulic servo device, to the control shaft 2 of the fuel injection pumps of the engine. Pivotally connected to the control rod it is one end of a balance lever l@ an intermediate point in which bears against an eccentric or cam controlled by a manual speed selection lever, while the other end of the balance lever lil bears on the upper end of the leak valve i6. The leak valve ill is formed as a solid cylindrical piston sliding in the upper part of the first chamber d, the lower surface of the valve bcing subject to balance pressure which thus urges the valve upwards into contact with the end of the balance lever it, while the circumferential sur face of the valve is formed with a curved out away 'portion 22, which permits hydraulic fluid at working pressure to escape from the gallery iii and thus constitutes the variable leak orifice through which the fluid discharges to relief.

It will be seen that a momentary increase in fluid flow, caused by an increase in engine speed, will be reflected in an increase in working pressure, relative to balance pressure, which will tend to move the working piston Q downwards and this in turn will tend to move the control rod I8 downwards. rlhe control rod l 8 also acts through the hydraulic servo device mentioned above to cause rotation of the fuel control shaft 2 in a direction to decrease the fuel supply to the engine. When the control rod l@ nieves downwards however the balance lever l pivoting about the speed selection cam 2u allows the leak valve le to move upwards, and so permits an increase in the flow of hydraulic fluid from the gallery i3 to relief, which decreases the working pressure and so lessens any tendency of the apparatus to produce hunting conditions. Rotation of the cam 2li alters the fulcrum of the balance lever is, and also adjusts the setting of the leak Valve i6, thus simultaneously controlling the speed at which the enthe second chamber 5 and subject on its upper side to balance pressure, is also loaded on its upper side by a double compression spring assembly, comprising a rst spring 2l bearing at one end on a fixed annular seating in the chamber and arranged to be operative at its other end on the stop piston lll throughout the travel of this piston, and a second spring 22 acting on a sliding sleeve whose movement in a downward direction is limited by a stop member 24, so that the second spring 22 becomes operative on the stop piston Ill only when the piston moves upwards past a predetermined position. The lower side of the stop piston E63 is subject to the pressure of fluid on the high. pressure side of the pressure reducing valve l, that is to say to pump delivery pressure, by means of a fluid connection 25 between the lowest parts of the rst and second chambers, 4 and this fluid connection 2b including a restricted orice to dampen any sudden movement of the stop piston. The stop piston is formed integral with a central downwardly projecting Well 26 which is effectively closed at its upper end by an apertured plate or flange, upon which the compression spring `2i bears, and the lower part of the control rod I3 passes freely through this aperture.

The lower end of the control rod i8, where it extends downwards below the aperture in the plate or flange closing the well in the stop piston, is provide-d with an enlarged head 2l, which prevents 'the end cf the rod passing upwards through the aperture, and causes the control rod to be drawn or held downwards when the stop piston moves sunciently downwards.

In normal operation the control rod I8 slides freely through the aperture in the stop position lli, and the biassing spring associated with the lost motion connection between the working piston 9 and the control rod IB causes the control rod and working piston to move together as a single unit. If however the pump pressure, that is to say the engine speed, is such that the stop piston lll takes up a position in which the head 21 of the control rod I8 engages the plate or flange closing the upper end of the well in the stop position lil f further upward movement of the working piston 9 will act to compress the biassing spring in the lost motion device, and the control rod will not be moved upwards. The lower limit of the travel of the stop piston is limited by an adjustable stop member 28 mounted in the lower end of the second chamber 5. This arrangement provides an over-fuelling control to prevent excessive amounts of fuel being supplied to the engine at any speed.

The extreme upper end of the control rod I8 is pivotally connected through a linkage 29, 30 to a forked arm 3l connected for rotation with the control shaft 2 of the fuel injection pumps. An intermediate point 32 on this linkage is connected to the control valve 33 of the hydraulic servo device, which valve is arranged in. known manner to direct hydraulic pressure fiuid derived from a second displacement pump 34 mounted in the same casing with the pump l selectively to the chamber on either side of a double-sided servo piston 35 and to connect the other of said chambers to relief. The servo piston 35 is pivotally connected to the forked arm 3i on the control shaft 2 of the fuel injection pumps.

The upper end of the cylinder in which the servo piston 3.5? lines is provided with a Derma.- nent bleed 3G to relief (not shown in Figure 1, but shown in detail in Figure 3) and the lower side of the servo piston is connected to a return rod 37 extend-ing downwards into an auxiliaryl chamber 33 containing a return spring assembly which acts in an upwards directionv on the return rod 3,1 tor bias the servo piston 35 towards its idle position corresponding to engine idling speed. The return spring assembly fulfills a double function and to this end also bears downwards on a so-calledv booster valve du, which controis the flow of fluid from the second servo displacement pump 311 into the lower part of the auxiliary chamber 3.3 and thence either directly to relief or to the hydraulic fluid tank 5i), whence it. flows back to av reservoir. This hydraulic circuit constitutes the. normal relief circuit for the hydraulic servo. system.

The booster valve 4G includes an air bleed valve of known. kind which will. pass air but not oil. (not shown in Fig. 1 but shown in detail in Fig. 4,), and discharges through a restricted bleed orifice into the same auxiliary chamber, which is. hydraulically connected to relief, or to tank pressure.

The hydraulic control mechanism described above with reference to the diagrammatic drawing ofY Figure 1, will now be described in greater detail by reference to Figures 2, 3 and 4, and 5 in which parts shown diagrammatically in Figure 1 are given the same reference numerals for ease of understanding, while subsidiary parts associated therewith are given numeral suffixes (for example the part 'H is associated with the part l).

One pinion, the driven pinion, of the positive displacement gear jump l is shown in half section in Figures 3 and d. The driven pinion is connected for rotation with the shaft 38 which is. driven from the engine crankshaft at a speed proportional to engine speed. One pinion of the second displacement pump .34, which is also, driven from the same shaft 33, is also shown in. half-section in. Figures 3 and 4.

Referring rst to Figure 2', hydraulic fluid under pressure is supplied from the gear pump i. through a cond-uit (not shown) to the. lower mosty annularA chamber 'H adjacent the pressure reducing valve '1. The valve 'l comprises a frustoconical element l2 lying at least partly within. a cylindrical bore in the chamber 4, and' a spring assembly including a spring 'I3 and an end cap lll, the upper end of the spring l?. be` ing arranged. to bear against an abutment plate 'l5 located in a, shoulder formed inl the chamber 4. In operation the valve 'l lifts against the-Dressure of the spring 13 and pressure uid passes around the conical element T2 into the annularv cham-ber a, and thence to the space 8l below the leak valve lr6. As mentioned, the characteristics cf the valve are so designed that the pressure drop across the valve is proportional to the fluid flow through the valve.

The annul-ar chamber 8 communicates with the centre part of the second chamber 5, and thel hydraulic fluid at balance pressure exerts an upward force on the lower side of the working piston 5l. The working piston 8 is urged downwardly by a springv il abutting against a fixed shoulder in the upper part of the chamber 5, and the piston is connected to the control rod I8. by a spring-biassed lost-motion connection including. a collar or spring seating 92. secured to, the rod, and a compression .spring S3 which bears; at. one end on the collar 9.2 and; atthe other end'. on the piston 9 and urges the piston down wards relative to the rod against an; abutment SM1' secured to the rod below the piston.

The stop piston ld is arranged in the lower part of the second chamber 5, and is formed'. inftegral with the well 26 which lies in a subsidiary chamber 5l' below the chamber 5., the downward limit of movement of the piston I0. thus being determined by the position ofA the adjustable; stop 28 which abuts against the lower end of the well 26. Fluid from the annular chamber 'll is admitted to the lower side of the stop piston through the restricted orifice i6 and the passage 25.

The stop. piston l is. downwardly biassedv by a spring assembly including a compression` spring 2i acting between a xed annular abutment llll arranged in the valve chamber 5 above the pis ton l0., and an apertured plate |02A resting on an internal. shoulder formed in the piston lll abovev the well 26.. The spring assembly also in.- olndes al second compression spring 22 acting' between the annular abutment lill and a flange at the lower end of a sliding sleeve 23, the sleeve. 23 having an enlarged radial flange 2li formed; at its upper end which engages the fixed abutment lei to limit the downward movement' of the sleeve. The bore of the sleeve 23 is, considerably larger than the diameter of the con-- trol rod i8, and thus pressure fluid is permitted to pass freely from the annular chamber 8 to the space below the working piston 9.

The lower end lill of the control rod I8, which passes. freely through the apertured plate H12 in the stop piston lil, is screw threaded to re. ceive an adjustable head 2l', which is larger thanthe aperture in the plate m2'. As described above, movement of the control rod in an upward direction is limited by the engagement of the head 2l with the plate |02 on the stop piston, and the relative strength of the springs l1, 93, 2l., and 22, is so designed that, on such engagement, the springs i? and 93 are distorted to allow the working piston to move relatively to` the control rod, while the control rod itself is located by the position of the stop piston.

The upper end of the control rod I8 is pivotally connected to the balance lever I9, and is rigidly secured to an extension i852, which acts through the hydraulic follow-up servo mechanism (shown in greater detail in Figure 3) to control the movement of the forked arm 3| and thus of; the shaft 2 controlling the supply of fuel to the engine. The remote end of the balance lever I9 is formed with a groove on its under side which bears against the domed head ISI attached to the upper end of the leak valve I6. Any intermediate point in the upper surface of the balance lever le bears against the speed selection cam 2li which is mounted for rotation on a shaft 2i extending outside the apparatus and connected to an operators manual speed selection lever (not shown).

The release valve I l, which is shown diagrammatically in Figure 1 as lying inv the same gen eral plane with the valve chambers d and 5.. is in the practical embodiment for convenience, and compactness arranged in a plane normal. thereto and is illustrated in detail in Figure 5.. Pressure fluid at balance pressure from the lower side of the working piston 3 passes through. the ports '5,2 (see Figure 2) into the space 13 ade jacent to the lower end of the valve chamber 6. and thence through the ports 64 (see Fig. 5).

to the interior of the release valve i i. The valve H. is of the sleeve type and is arranged to slide in a cylinder 6I defining the valve chamber E. The valve Il is formed integra-1 with a piston l2 closing its upper end and the lower end of the valve cooperates with one or more ports (shown in dotted lines at 62) to permit pressure fluid to pass into the gallery i3 surrounding the valve chamber. The valve ii is spring loaded in a downward direction by a spring H2 abutting against a fixed plug H3 at the upper end of the chamber 6 and the plug H3 is provided with an aperture through which the space above piston i2 communicates with the internal cavity 5S which is sub-ject to tank pressure. Downward movement of the valve i l is limited by the fixed tubular member H3, and in this lowest position the ow of pressure fluid through the port 52 is shut ofi. The valve in normal operation thus acts as a pressure release valve, the valve piston l2 being subject to the difference between the balance pressure and tank pressure (or relief as the case may be).

IThe valve i i is also arranged to act as a relief or safety valve for this part of the hydraulic circuit and to this end the upper part of the valve sleeve is provided with a series of circumferentially spaced ports lil, which permit pressure fluid to pass into the chamber on the upper side of the valve when the valve rises beyond a predetermined point.

The hydraulic follov/up servo mechanism arranged between the control rod I8 and the control shaft 2 associated with the fuel injection pumps is shown in detail in Figure 3. The extension E32 on the upper end of the control rod IS is pivotally connected to the lever 29 which is in turn connected through the link 3u to the forked-arm 3 l. An intermediate point 32 in the length of the lever 29 is connected through the link 331 to a balanced piston-type control valve 33 having piston formations 332, 1333 at opposite ends. Pressure fluid from the displacement pump 3ft is admitted through a fluid conduit (not shown) to an annular chamber 33t which communicates through ports 335 with the annular space between the two piston extremities the valve 33. Ports 333 adjacent tothe upper' end of the Valve 313 communicate through ports with the interior of the upper end of the chamber 352 within which is mounted a doublesided servo piston 35. Similarly ports 331 adjacent to the lower end of the valve 33 communicate with the lower end of the chamber 352 below the servo piston 3E. The valve 33 thus acts as a reversing control valve selectively to conneet one side of the servo piston 35 to pressure and the other side to relief.

The upper end of the chamber 352 is provided with a permanent bleed 36 to relief, including a plug SES screwed into the upper end of the cylinder and having a restricted aperture 382 which communicates with a screwthreaded nipple 363 through which a steady flow of hydraulic fluid is discharged even when the servo piston 35 is stationary.

' The servo piston 35 is rigidly connected to a return rod 3l which passes through a gland in the lower end of the chamber 332 and is formed with a longitudinal diametral slot 374 transfixed by a pin 3l? supporting a flattened bushing .3?.3 which is an accurate sliding fit in the forked part of the forked arm 3i. Movements of the control rod iB thus act initially to move: the control valve Sii-so as to introduce pressure iiud to one side or other of the servo piston 35, which in turn provides power assisted operation of the control shaft 2. rflue consequent movement of the forked arm 3i acts through the follow-up linkage 23 and 33 to close the control valve 33 until such time as further movement of the control rod iii causes this valve to open again.

The combined booster valve and return spring assembly for the return rod 3l is shown in detail in Figure 4. The lower end of the return rod 3l is a sliding fit in a sleeve 374 extending through the upper wall of the cylinder 462, and is provided with a spring seating 43| to receive the upper ends of two helical compression springs 563 and litri. The lower ends of the springs 403, Mii rest on a flange-like seating secured to the sleeve-type booster valve 40, which is a sliding fit en an internal tubular valve member S35 formed with circumferentially spaced valve ports llil. Pressure fluid from the pump 38 is supplied throgh a hydraulic connection (not shown in Figure 4) to the lower end of the tubular valve member 4% and exerts an upward thrust on the closed upper wall of the valve d@ to open the ports 1593 against the action of the springs 453, dell. The upper wall of the valve di? is provided with a restricted air bleed comprising a plug formed with a small drilling or restricted aperture titl' designed to pass air only. Having passed through the ports 436 the hydraulic iiuid which may be at a relatively high temperature due to the dissipation of energy when passing through the ports is returned to the hydraulic reservoir through the connection ABS.

A manual operating control assembly is prov'ided in association with the control shaft of the fuel injection pumps to enable an operator t0 over-ride the governor for starting or stopping purposes for example, or in the event of a governor failure. The assembly is shown in detail in Figures 6, 7, 8 and 9. The control shaft 2 of the fuel injection pumps of the engine is connected to the forked arm 3| under the control l of the governor, through a dog clutch, comprising a dog sleeve 4I splined to the shaft 2 and having one or more axially extending dogs 4H (see Figure 8) arranged to engage with recesses M2 between cooperating dogs in the forked arm 3l, the dog sleeve 4I being axially slidable on splines 453 provided on the shaft 2, and being urged into the engaged position by a spring H4 surrounding the shaft. A manual operating control lever M5 is rigidly mounted on an over-ride sleeve did surrounding the shaft 2 on the side of the forked arm 3l remote from the dog clutch, this over-ride sleeve 4l@ extending within the forked arm and being formed at its end adjacent the dog sleeve 4I with one or more circumferential recesses dil' of approximately 59 arcuate length, arranged to cooperate with the dogs il l. of these recesses il? is formed with a fiat side at one end, and an inclined portion M3 sloping axially outwards to half the depth of the recess at the other end. Movement of the manual operating lever il 5 in a direction to reduce the fuel supply to the engine will eventually cause the dogs il I on the dog sleeve 4i to ride up the inclined portions H3 of the recesses 4I? on the over-ride sleeve M3 and thus will disengage the dog sleeve il from the recesses H2 in the governor controlled forked arm 3i. Further movement of the manual operating control lever 4&5 in the same direction will then cause the dog sleeve fil and thus the control shaft 2, 'to rotate and'so stop the engine. Conveniently the manual operating control lever 4l5 is provided with a slot 4l9 cooperatingv with a roller 420 on a crank arm 42| connected for rotation with a pulley 422, which is mounted eccentrically in rela-- tion to the shaft 2, and which may be operated remotely by means of a beltor wire from a further pulley (not shown) under the control of the operator. The shaft 2 is secured to an output arm 428 which is arranged to operate the engine fuel pumps.

An additional emergency control' is provided to enable an operator to over-ride the governor entirely. For this purpose the manual operating control lever 4|5` is provided with a releasable spring-pressed plunger 423 (see. Figure 9) which is arranged to pass through a locating bore in the over-ride sleeve 41B into a locating recess 424 in the control shaft 2. To operate the emergency control the operator releases the plunger by rotating the head 425 until the Webs 426 engage the slots 421, and rotates the control lever M in a direction to reduce the fuel supply until the over-ride sleeve 416 causes the dog sleeve 4l to become disengaged from the forked arm 3l. In this position the plunger E23 passes through the locating recesses, and the control lever :H5 is thus locked to the control shaft 2 for manual control, while the forked arm 3| and thus the governor, is held out of engagement.

This arrangement also provides for easy reengagement of the governor when desired. What I claim as my invention and desire to secure by letters Patent is:

1. Hydraulic governor apparatus for an internal combustion engine comprising a displacement pump driven at speed proportional to that of the engine, a speed control member arranged to control the speed of the engine, a working piston associated with the speed control member and acted upon by. pressure derived from the pump, a leak valve arranged in the hydraulic circuit of the working piston to control the escape of uid from the said circuit, the said leak valve being connected with the working piston so as to be moved automatically in response. to move-- ments of the piston to dampen the movements of the piston, means for adjusting the datum setting of the leak valve to control the speed at which the engine is to operate,A andl apparatus to limit the supply of fuel to the engine at any particular engine speed comprising a movable hydraulic stop, and means for varying the position of the said stop in accordance with engine speed, the said stop being arranged to resist movement of the speed control member, in a direction to increase the speed, beyond a point which thus varies with and is determined by the engine speed.

2. Hydraulic governor apparatus as claimed in claim l in which the movable stop comprises an hydraulic stop piston, which is subject on one side to. hydraulic pressure derived from the said displacement pump.

3. Hydraulic governor apparatus as claimed in claim l in which the working piston is doublesided with the chamber of one side connected to the delivery side ofthe displacement pump i while the chamber on the other side is connected to relief through the said leak valve, and includ'- ing` a spring urged release valve arranged in a hydraulic connection between the two chambers, whereby an increase in the fluid flow from the displacement pump is renected as an increase in pressure on the low pressure side of the working piston relative to the pressure on the high.

5. Hydraulic governor apparatus as claimed inA claim 4, in which the working piston and the hydraulic stop piston are arranged at opposite ends of a single cylinder, the pump delivery pressure being admitted direct to the side of the stop piston remote from the working piston, while the low pressure side of the pressure reducing valve is connected to the intermediate part of the single cylinder between the working piston and the stop piston, the side of the working piston remote from the stop piston being subject to the so-called working pressure between the release valve and the leak valve.

A6. Hydraulic governor apparatus as claimed in claim 5, including a lost motion connection between the hydraulic stop piston and the speed control member of the engine, and a resilient connection between the working piston and the speed control member of the engine, such that within the limits of the lost motion connection the speed control member is controlled by the working piston, whereas for movementv of the working piston beyond such. limits the resilient connection is distorted, and the speed control member is controlled by the stop piston.

7. Hydraulic governor apparatus as claimed in claim 6, including a spring assembly varranged to act on the stop piston, said spring assembly com prising a rst spring which is operative throughout the travel of the stop piston, and a secondv spring which is operative only at positions of the stop piston corresponding to relatively high engine speeds.

8. Hydraulic governor apparatus as claimed in claim 1, including a lost motion connection between the hydraulic stop and the speed control member of the engine, and a resilient connection between the working piston and the speed control member of' the engine, such that within the limits of the lost motion connection the speed control member is controlled by the working piston, whereas for movement of the working piston beyond such limits the resilient connection is distorted, and the speed control member is controlled by the stop piston.

9. Hydraulic governor apparatus as claimed in claim l, including a manual operating control connected to the engine speed control member, and an over-ride mechanism which, on movement of the manual operating control through a predetermined distance towards its stop position, acts to disconnect the working piston from the engine speed control member, so that further movement of the manual operating control towards its stop position acts to reduce the engine speed.

1G. Hydraulic governor apparatus as claimed in claim 9, including a clutch between the working piston and the engine speed control member,l resilient means tending to urge the parts' of said clutch into engagement, a lost-motion connection between said manual operating control and said engine speed control member, and means acting to disengage said clutch in response to predetermined movement in said lost-motion connection.

11. Hydraulic governor apparatus as claimed in claim 10, including an emergency control device arranged to lock the two parts of said lost-motion connection in a position in which said clutch 10 2,481,334

14 is disengaged, whereby the governor working piston is disconnected, and the manual operating control becomes solely effective to control the engine speed control member.

References Cited in the le of this patent UNITED STATES PATENTS Name Date Nicolls Sept. 6, 1949 Number 

